I should be finishing my MkIII build some time next year, and started wondering about what the fuel mileage will be like, and what kind of highway range I can expect. I should have 500+HP out of a small block with a Holley SA 670, road-race TKO 600, 17" wheels, a mustang fuel tank (with a sump added to it), and either 3:31 or 3:55 gears.
My dd, a Jeep SRT8, gets about 11.5 MPG and has a range of 200 miles in regular driving, and on the highway gets about 16-17 MGP which pushes the range out to around 280 miles or so. I don't mind in the sllightest since it's a blast to drive, and fairly quick (0-60 in 4.5). My Rune gets about 27/36 MPG, but only holds just over 6 gallons of useable fuel. That outs the range right around 150/215 miles. I usually need to fill the bike up every other time I take it out, and have ridden it cross-country to the Carolinas, so I'm cool with that, too.
I don't really care about what the mileage in the roadster will be, but I was just curious about it. I'm going to guess that with my driving style, it'll be close to the Jeep's mileage and range, if not a little better, since I won't be able to use full throttle nearly as much I do in the Jeep.
My sbf 347 efi with T-5, 15"wheels, 3:55s,ect gets 22.64mpg. My motor is only maybe 400fwhp -ish? Me thinks you should get 14-16ish mpg with 500hp(maybe). Good luck & keep us posted--
hth
Butch
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This ain't no circus--and I don't need any clowns!
I have a SBF 363 with 500 HP (quick fuel HR780 carb), TKO600, 3.55 gears, 15" wheels, 15 gallon Mustang gas tank. Around town I get about 10 mpg, if I just cruise on the highway @65mph i'll get about 18-20 mpg. Around town I get about 110 miles until I fill it up and highway about 240 miles.
Wow! Thanks for the replies. If it beats the Jeep on fuel mileage, I might have to make it my new daily driver! You know, just because!
I will certainly be posting up when I resume the build. Been doing research for a few years now, so I have a LOT of decisions yet to be made, but it's gonna be cool.
My 416rwhp/426rwt 347 gets 8mpg and no one can figure out why, I have to fill up every 120 miles. Chances are it's my tuning but I am done tossing money around trying to get it running perfect.
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MKII non donor
347 stroker with stacks
3 link, Koni front & rear, 4 wheel disc brakes
Operation Chrome Elimination Underway
My 428FE (im guessing somewhere around 370 bhp) gets a whopping 13mpg highway and 9mpg when im heavy on the pedal. The 15 gal mustang tank gets on my nerves, i have to stop and fill up every 120 miles or so. My dd is a civic so i'm used to stopping once a week for gas not every day.
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FFR MK4 7285 IRS 428FE PSPB TKO600
Delivered 8/10/2010
Graduate Auburn 12/13/2010!
First Go-Kart 12/18/10
Paint 7/3/11
On the Road 11-11
I have a 408W with a TKO600 and 3.55 gears. I was running fuel injection and was getting around 13-14 mpg highway, and about 10 around town (this was one of Wayne's stack injection setups). It had too many tuning issues so I ended up pulling off all the EFI stuff and stuck a QuickFuel 750 double pumper on it. MPG went up to about 16 on the highway, and 12-13 around town. I have a 22 gallon fuel cell in the car, so I can comfortably get 200 miles on a tank - so something similar to your Jeep I guess. FWIW the carb runs much better than the stack injection system ever did. I took it to an autocross a week or so a go, and I posted my best finish yet - 8th out of 29 in my class - not too bad considering most of the guys ahead of me were on slicks, and I was within a second or so of most of them.
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Howard
408W, IRS, TKO600, PS, PB, QF SS 750, POM Sept 2010.
FFR 6817 // Delivery Date: 11/20/08 // Roller: 9/25/09 // First Engine Start: 3/31/10 // Gokart: 4/11/10 // Painted: 7/2/10 //Graduated 10/03/10. Graduation thread with my progress links is here.
from experience...with less hp, mileage probably will be the same as your Jeep or less. Depending on your driving style you can empty the tank in two hours with spirited driving or two days cruising around town. Not much more than that.
I don't think your gonna get 500++ HP with a SA670 Holley. Its set up more for a mild build. The throttle bores are the same as a 600cfm Holley. I had one and it was too lean on light throttle accelleration. A 650 double pumper made a big difference but mileage dropped a lot, kinda too far the other way.
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331, RPM intake, TW heads, TF STG II cam, 3:55, powerjection III, 3550 trans, NT-03M Enkei 18x8.5 & 9.5, Kumho XS 245-40 \ 275-35, 3-link, Fast Freddies PS, ABS
396 c.i. guessing 400 + hp (?) EFI and 3.73 rear gears gets me 15 mpg on the highway and 12-13 around town. Hope I've done the math right (we sell fuel by the litre here and my speedo reads kms )!
Sean
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Mk III partial SN95 donor, 351W stroked & poked to 396 c.i., custom EFI, 4 into 4's, 3link, 3.73, chrome FR500's, full bumpers, 2 X roll bars, I² electronics, hydroboost, 5-lug, GT front, MK VIII/Cobra rear discs, painted by SRP, (fully) legal and driving! Graduating...?
I don't think your gonna get 500++ HP with a SA670 Holley. Its set up more for a mild build. The throttle bores are the same as a 600cfm Holley. I had one and it was too lean on light throttle accelleration. A 650 double pumper made a big difference but mileage dropped a lot, kinda too far the other way.
Yeah, you're right. It's an 870. Not sure why my brain made me type 670
I installed a KC 408 with 530 hp at the flywheel. 3550 with 3:55 gears and 26" wheels.
Mike got 6.7 mpg and called me about it. I set him with Coach Mike our carb guys who has the same motor in his Coupe.
After tuning the carb Mike got 13.5 mpg.
Not bad for a couple of jets and a hour of time.
Dwight
P.S my 303/354 EFI stroker (402 rwhp) got 21 - 22 on my 1150 mile trip to the London Cobra show with 10 or so passes down Maint Street.
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Lone Star Cobra 354 ci (3.47" x 4.03" 302 motor) EFI 402 rwhp & 416 rwtq with 37,000 miles, Custom Painted 06 Mustang & RCR GT 40, 302 with Eight Stack Injection system
5.0, EFI, "E" cam, Custom headers, T5, Mustang tank, 3.73's turning 315 x 17 tires = 22 highway at a sustained 80 mph, 18 around town with a bit of a "heavy foot" syndrome.
Doc
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little block, BIG BLOCK . . . HUMMMMMMM? FFR3712K (POPSDRM) in Lost Wages, NV. MKII, 5.0, GT40-EFI, E-303, T5, 17" 5-Lug Chrome Cobra "R's", 315's, PBR 4 wheel Disks, Full Tubular suspension, Flaming River, 3.73:1 3-Link, Drop Butt mod, Dash forward mod, Footbox Air vents, Custom Turn Signals, Custom 4-into-4 headers, Non-Donor build, Ford Royal Blue Pearl w/ Arctic White stripes.
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. My motor is only maybe 400fwhp -ish? Me thinks you should get 14-16ish mpg with 500hp(maybe). Good luck & keep us posted--
Miss Canada
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